SiCOH film preparation using precursors with built-in porogen functionality

a technology of porogen and precursor, which is applied in the direction of liquid surface applicators, coatings, chemical vapor deposition coatings, etc., can solve the problems of increasing signal delays in ulsi electronic devices, affecting the production efficiency of sicoh dielectrics, and not being thermally stable, etc., to achieve better mechanical properties, improve film properties, and improve the effect of porosity control

Active Publication Date: 2007-07-12
TAIWAN SEMICON MFG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0013] More specifically, the present invention describes methods for fabricating a layer of a SiCOH dielectric material having improved film properties, which is uniform in atomic and structural composition, both when measured across the substrate diameter, and through the depth of the layer, that does not exhibit variation in the process or process instability. Further, the dielectric films of the present invention have a pore size on the nanometer scale without the presence of larger pores, and hence the distribution of pores sizes is uniform and narrow.
[0014] The use of the inventive methods with deposition of a preliminary film from one or more, preferably a single, organosilicon precursors containing a built-in sacrificial organic porogen enables better control of the porosity in the final film and a narrower pore size distribution, resulting in better mechanical properties at the same values of dielectric constant. Furthermore, the deposition of a preliminary film from the organosilicon precursors described herein enables improved mechanical properties of the final SiCOH dielectric film.

Problems solved by technology

This combined effect increases signal delays in ULSI electronic devices.
Most commercially available dielectric materials, however, are not thermally stable when exposed to temperatures above 300° C. Integration of low k dielectrics in present ULSI chips requires a thermal stability of at least 400° C.
It is also commonly found that SiCOH dielectrics made in the prior art from two or more separate organosilicon and / or porogen molecules are not uniform in atomic and structural composition, both when measured across the substrate diameter, and through the depth of the dielectric layer.
The use of 300 mm Si wafers has made this problem of chemical uniformity across the wafer more pronounced.
Additionally, prior art CVD SiCOH dielectrics made from two or more separate organosilicon and / or porogen molecules were found to exhibit process variation or process instability due to small changes in the flow rate of one of the two precursors, known to those skilled in the art as drift in the flow rate.

Method used

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  • SiCOH film preparation using precursors with built-in porogen functionality
  • SiCOH film preparation using precursors with built-in porogen functionality
  • SiCOH film preparation using precursors with built-in porogen functionality

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first embodiment

[0059] Referring to Scheme 1, R═alkyl, R1 and R2 may be alkyl, aryl, or alkoxy, R3 may be hydrogen, alkyl, aryl, cycloalkyl or alkoxy and R4 may be alkyl, aryl or alkoxy. Moreover, the reactions are shown to provide a route to polymerizable precursors where the silicon substituents are separated by a two-carbon bridge (Si—CH2—CH2—Si bonding unit). At the top of Scheme 1 are example starting materials within the These molecules are substituted derivatives of disilane. Shown at the top of Scheme 1 are highly substituted disilane derivatives, but related molecules with fewer alkoxy (OR) substituents may be used within the invention. Fluorine and chlorine substituents are also acceptable for the subsequent oxidative addition. The starting material may be symmetrical or unsymmetrical. A preferred substituent is alkoxy and most preferably multiple alkoxy substituents as shown at the top of Scheme 1 are used. The disilane bond is prone to oxidative cleavage and addition to Pi bonds in the...

second embodiment

[0063] Within the second embodiment, the precursors (31) and (33) are converted to a cyclic precursor or a prepolymer prior to forming the preliminary film. Referring now to Scheme 2, precursor (31) wherein at least one of R1 or R2 is R*, preferably an alkoxy, further transformed by acid or base-catalyzed hydrolysis. Typically, the starting material is dissolved in methylene chloride and treated with 0.1N aqueous HCl solution at 25° C. for 24 hrs. The volatiles are removed and the residue redissolved in methylene chloride and dried over 4 Å molecular sieves. Higher dilutions favor the formation of cyclics when only two alkoxy substituents are present in the starting materials (K. Rahimian et al Chem. Mater. 2005, 17, 1529).

[0064] Depending on the stereochemistry of the oxidative addition, reaction with one equivalent of water can produce 2-oxa-1,3-disilylcyclopentanes containing additional finctionality for subsequent condensation, as shown in Scheme 2. Path A, producing precursor...

third embodiment

[0066] Referring now to Scheme 3, a third embodiment within the invention is shown in which a related synthetic procedure is applied to norbomene substituted monomers. This embodiment builds a Si—C copolymer that contains subunits related to a successful organic porogen molecule bicycloheptadiene (norbomadiene). First precursor (39) is selected, and the preliminary film contains the structure shown schematically as (41) formed by hydrolysis and condensation and is coated on the substrate. In step (42), controlled heating causes the loss of the polycyclic hydrocarbon fragments by retro Diels Alder reaction, forming a network organosilane containing bridging ethylene segments (43), a further stage of the preliminary film.

[0067] The steps of FIG. 2 which shows hydrolysis steps; in the above, the hydrolysis / condensation occurs in 3A, are applied. The double bonds in (43) are further incorporated into the final film and converted to single bonds during the energetic treatment step with...

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Abstract

A method of fabricating a dielectric material that has an ultra low dielectric constant (or ultra low k) using at least one organosilicon precursor is described. The organosilicon precursor employed in the present invention includes a molecule containing both an Si—O structure and a sacrificial organic group, as a leaving group. The use of an organosilicon precursor containing a molecular scale sacrificial leaving group enables control of the pore size at the nanometer scale, control of the compositional and structural uniformity and simplifies the manufacturing process. Moreover, fabrication of a dielectric film from a single precursor enables better control of the final porosity in the film and a narrower pore size distribution resulting in better mechanical properties at the same value of dielectric constant.

Description

RELATED APPLICATIONS [0001] The present application is related to co-assigned U.S. application Ser. No. 10 / 964,254, filed Oct. 13, 2004, entitled “ULTRA LOW k PLASMA ENHANCED CHEMICAL VAPOR DEPOSITION PROCESSES USING A SINGLE BIFUNCTIONAL PRECURSOR CONTAINING BOTH A SiCOH MATRIX FUNCTIONALITY AND ORGANIC POROGEN FUNCTIONALITY”, the entire contents of which is incorporated herein by reference.FIELD OF THE INVENTION [0002] The present invention generally relates to a method of fabricating a dielectric material that has an ultra low dielectric constant (or ultra low k) using at least one organosilicon precursor. The organosilicon precursor employed in the present invention includes a molecule containing both an Si—O structure and a sacrificial organic group, as a leaving group. The use of an organosilicon precursor containing a molecular scale sacrificial leaving group enables control of the pore size at the nanometer scale, control of the compositional and structural uniformity and si...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H01L21/31
CPCB05D1/60C23C16/30C23C16/56H01L21/02126H01L21/02203H01L21/31695H01L21/02274H01L21/02282H01L21/02337H01L21/02348H01L21/02351H01L21/02216
Inventor GATES, STEPHEN M.GRILL, ALFREDMILLER, ROBERT D.NEUMAYER, DEBORAH A.NGUYEN, SON
Owner TAIWAN SEMICON MFG CO LTD
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